Focaccia barese

Step 1: Stir ⅛ oz dried yeast and 1 tsp sugar into 1 ½ cups lukewarm water and leave for 5 minutes.

Step 2: In a large bowl mix 9 oz semola rimacinata (fine durum wheat semolina), 9 oz 00 flour or strong white flour and the cooled mashed 5 ½ oz floury potato. Pour in the yeast water and stir to a shaggy, sticky dough.

Step 3: Add ⅓ oz fine salt and work the dough in the bowl with a wet hand for 8 minutes, slapping and folding it, until it turns smooth and stretchy. It should be very soft and sticky; do not add more flour.

Step 4: Cover and leave in a warm place for about 1 hour 30 minutes, until doubled and full of bubbles.

Step 5: Pour 4 tablespoons of 3 tbsp extra virgin olive oil into a 30–32 cm round metal pan (or two 24 cm pans) and spread it over the base and sides.

Step 6: Tip the dough into the pan with oiled hands. Press it out towards the edges; if it springs back, wait 10 minutes and press again until it fills the pan evenly.

Step 7: Halve 10 ½ oz ripe cherry tomatoes and squeeze each one over the dough as you press it in, cut side down, so the juice runs onto the surface. Push 2 ⅞ oz green or black olives in between.

Step 8: Dimple the whole surface with your fingertips, sprinkle with 1 tsp dried oregano and ½ tsp coarse sea salt and drizzle over 3 tbsp extra virgin olive oil. Leave to rise for 20–30 minutes, until puffy. Heat the oven to 450°F (400°F fan) with a rack at the bottom.

Step 9: Bake on the lowest rack for 25–30 minutes, until the top is golden with darker edges and the base sounds crisp when you tap the pan. Common mistake: baking on a high shelf; the top colours before the base has fried in the oil, and the bottom stays pale and soft.

Step 10: Slide the focaccia out onto a rack and cool for 10 minutes before cutting into wedges. It is best eaten warm or the same day.